A USB oscilloscope:
https://www.amazon.com/gp/product/B00GZMRZ3M/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
Gave away my huge/heavy Tektronixs decades ago when it broke down, to a co-worker who was going to try to fix it. Since then, I wish I had one every once in a while, but couldn't justify another box taking up room on a shelf when I might use it a couple times a year or something.
I had previously looked for a USB scope, figuring a laptop has the screen and power for this, so all I would need would be the "front end" amplifier and sampler. But the reviews of the affordable units were pretty poor, plus I wanted Linux support, and that limited me a little more.
I don't now if I missed this one before, but I recently came across some positive reviews for it. You can download the software from their site, and try it in a demo mode. I was impressed. It's the same software they provide with their much more expensive scopes. So I bought this entry-level 2204A version, limited to 10 MHz, but that's OK for what I do. Played with it the last two days a little, am very impressed with everything. Has a built in Waveform Generator, you can even create your own arbitrary waveforms, or 'pull' them from a wave you captured on the screen. Convenient to save the set up and screen capture to a file, or do a screen grab to document your work. Here's an example of the switching power supply on a cheap solar garden light. These now have a little 4-pin IC (like a one-leg-wider plastic transistor package), with just the solar cell, AA rechargeable, the LED and a single inductor - does it all. So now I know, the switching frequency is ~ 275 KHz.
I just might build a DC-coupled amplifier for the wave generator, you can program the offset, so I could use it as a programmable power supply, which might be handy for some projects. Might be convenient to us that to ramp the voltage while I capture a waveform to characterize a device.
-ERD50